Omnidirectional ball-drives that are used in propulsion devices rely upon two drive motors that rotate two corresponding drive gears to transfer energy into ball motion. The drive gears contact the ball on two orthogonally adjacent sides. The drive gears are either rotated forward or backward to accomplish omnidirectional motion. Being located on the side of the ball, each drive gear requires an opposing friction-free roller in a line parallel to the surface being traversed.